Boards of lumber produced at a sawmill or the like may exhibit defects which adversely affect the quality of the material and which may make it unsuitable for intended uses. Knot free boards are desirable for some purposes. Knots make it difficult to prepare a smooth finish on the surface of a board, may bleed pitch and have a tendency to loosen and drop out after a period of time. In other cases where knots are acceptable, there may be loose knots, split knots or knotholes which downgrade the quality of the lumber. Other forms of localized defect can also be present such as decayed areas, pitch pockets, impact damage or excavations made by birds or insects.
Such defects in boards of lumber or the like can be repaired and the quality of the lumber upgraded by cutting a bore through the board to remove the defective region and then filling the resulting opening with a filler material which may be a hardenable mastic or a plug formed of the same wood as the board that is secured in place with adhesive. The techniques heretofore used for repairing defects in this manner do not provide optimum results. The plug of filler material is held in place in the opening in the original wood solely by adhesives and thus the plug can be loosened and ejected by impacts or other forces.
Prior board defect repairs also tend to require complicated installation operations such as the forming of openings in the wood and fabrication of conforming plugs that each have a convoluted shape for resisting twisting of the emplaced plug and for providing a greater area for application of adhesive. One prior process requires the complication of providing threads at the opening in the board and also on the plug so that a threaded engagement, reinforced by adhesive, can be effected. A threaded plug is not inherently locked into the wood and can be worked loose if subjected to sufficient torsional force.
A board repair which is more positively resistant to loss of plugs from openings in the original wood or the like would be highly advantageous.
The present invention is directed to overcoming one or more of the problems discussed above.